1. Field of the Invention
The present invention relates to a composition for delaying an on-site of cross-linking in formation fracturing fluid (frac fluids), to frac fluids including the cross-link delaying or retarding composition and to methods for making and using same.
More particularly, the present invention relates to a composition for delaying an on-site of cross-linking in formation fracturing fluid (frac fluids) and to frac fluids including the cross-link delaying or retarding composition, where the cross-link delaying or retarding composition includes an effective amount of a polyol, where the effective amount is sufficient to delay the on-site of cross-linking of hydratable polymers and/or phosphates esters in the frac fluid for a desired period of time. The present invention also relates to method for making and using same.
2. Description of the Related Art
One key problem with cross-linking systems used in formation fracturing fluids (frac fluids) is that the cross-linkers are needed to build viscosity quickly, but only after a delay sufficient for the fracturing fluid to be pumped into the formation without viscosity peaking in transit.
Many fracturing fluids and cross-linking systems have been proposed. Most fracturing fluids include a hydratable polymer that is cross-linked by a metal ion cross-linking system. These metal ion cross-linking system generally include a transition metal and some also include a borate or borate generating reagent. However, in all these systems, the cross-linking delay, if any, is inherent in the composition of either the cross-linking system or the fracturing fluid or both.
Thus, there is a need in the art for a composition that can be added to a fracturing fluid before, after or simultaneous with the addition of the cross-linking system to delay the on-set of cross-linking for a desired period of time, where the delay system can be used to tune the delay for optimal formation fracturing—timed and tuned viscosity build up.